The well known technique of dual-energy CT scanning separates materials whose absorption are energy dependent and has thus far been performed on medical CT scanner models with slow scan times and low spatial resolution. Bio-Imaging Research, Inc. has designed a medical CT scanner with a scan time as little as 1 second with continuous back-to-back scans using a slip-ring and having spatial resolution of 1.7 1.p./mm at cut-off. The scanner offers the opportunity to improve dual-energy investigation. Improved dual-energy scans on this system can offer minimal motion artifact, lower patient dose and high spatial resolution. This proposal consists of the development of a unique dual-energy scanning technique for high-speed and high resolution CT scanning that combines kVp switching and beam filtering to produce optimal separation results with minimization of spectra overlap. This technique can also be applied to any slower, lower resolution CT scanner with the benefit of lower dose exposure. Phase I includes spectra and attenuation computer models for optimal filter/kVp selection along with filter fabrication and implementation. Validation will include phantom and pig's head CT scanning.